I installed Win 7 pro on it and manualy added the drivers for the storage drivers.

Audio installed itself by default with Win7 as High definition audio.

Now here's the thing: My computer case had before by an HD connector for the front panel but it broke. The spare one installed is only AC'97 so what is happening now?

This is the type of older motherboard that you had littles blue jumpers on the motherboard audio connectors when the setup was not installed into a case equipped with front panel audio. It also worked with both AC'97 or HD audio.

Is the backpanel motherboard sound connectors are still on HD audio or they became AC'97 because of the front panel audio connector that now make the jumpers for the audio connectors on the motherboard?

This shows the difference between the AC'97 and HD audio front panels.

The main reason for the difference is to do with speaker assignment. With the older AC'97 system, only a single pair of stereo speakers was supported. These could be switched on and off by a standard switching stereo jack socket. With the introduction of HD audio, and the ability to feed upto 8 speakers (7.1 audio), a different method of muting had to be utilized. This method uses circuits built in to the audio chip itself to control the rear socket muting. All the front panel has to do is to provide the correct signals to the audio circuitry to tell it whether it should mute the rear panel or not. To do this, specially designed jack sockets are used. Inserting a set of headphones into the front panel socket will cause all rear panel sockets that have been assigned as speaker sockets to be muted. Since the rear microphone socket can also be re-assigned as a speaker socket, a similar arrangement also exists for a front panel microphone as well. This disables the rear pink (MIC) socket, but not if it is assigned as a speaker socket.

Note that an AC'97 style front panel WILL NOT mute speakers connected to the rear panel of a HD equiped motherboard - only a HD front panel is configured to do so.
Even cases that come with front panels fitted with both HD and AC'97 audio plugs for the motherboard will not mute these speakers as the jack sockets are still the type used for AC'97, meaning that the required muting signals are never received by the audio chip on the motherboard.

So in fact it will not change anything on the sound quality on my TV becaue the sound wire goes from the green back panel plug right into my tv. I think i prefer that so my computer dont send a 5.1 signal to a 2.0 speaker stereo mode tv.

Lucky that I have read it before listening to my usic. I have headphones with volume maxed out at 3 in the morning !!!